Why doesn't the silver needle bleed?

Theoretically, as long as the blood vessels are damaged and the blood vessel walls are broken, they will bleed. As long as it doesn't damage blood vessels, it won't bleed. The acupuncture needle is very thin, generally about 0.3 mm When it is inserted into the acupoint, it will not touch the blood vessels under normal circumstances, so it will not bleed. If it is intentional bleeding, it is a special acupuncture method, that is, it is deliberately allowed to bleed to achieve the purpose of treatment.